[Xen-users] Re: Use hard drive as physical mem for xen vm

[Charles Duffy <cduffy@xxxxxxxxxxx>]

If you want to force MySQL to use swap in place of physical memory, why 
not just find the place in the source where it checks for physical (vs 
virtual) memory and modify it to require only that adequate virtual 
memory be available?
Using virtual memory without the knowledge of the underlying OS is just 
a really, really, really bad idea. In-memory pages get rewritten 
*exceedingly* frequently in a great many cases -- unlike pages which the 
OS intelligently chooses to swap out, which are selected *because 
they're not frequently used*. If you're doing this behind the OS's back 
-- just mapping a big region of "physical memory" to disk -- then you no 
longer have any of those algorithms working in your favor, and the wait 
times will be *huge*.
As the other respondants have suggested -- don't do it this way. Modify 
MySQL instead.
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